Field of the Invention
The present invention relates to a failure detection device of a power converter and a vehicle with the same mounted therein. More specifically, the invention relates to a failure detection device that detects a failure of a temperature detection member and a vehicle with the same mounted therein, wherein the temperature detection member detects a temperature of a switching element mounted in a power converter.
Description of Related Art
Cars that run using motors such as hybrid cars, fuel-cell cars, and electric cars have become widespread in recent years. Such a car that runs using a motor has a voltage converter that boosts a voltage supplied from a battery, a power converter that converts a DC voltage that has been boosted by the voltage converter into an AC voltage and supplies the voltage to the motor, and the like, mounted therein. In addition, the voltage converter, the power converter, and the like are housed in a housing in which a water jacket for cooling down the devices is formed. A unit in which the voltage converter, the power converter, the housing, and the like are gathered is mounted in a vehicle as a power control unit (which may be abbreviated to a “PCU” hereinbelow).
A power converter includes a plurality of semiconductor chips which are formed by combining power semiconductor elements like insulated gate bipolar transistors (IGBTs), diodes, and reverse conducting IGBTs (RC-IGBTs), etc. In addition, since a high current flows in the power semiconductor elements, a temperature thereof significantly changes accordingly. For that reason, the semiconductor chips also include temperature sensors to detect temperatures. In addition, when such temperature sensors are provided, a failure detection device that detects failures of the temperature sensors is also provided in many cases (e.g., refer to Patent Literature 1).
With respect to a failure detection device of temperature sensors disclosed in Patent Literature 1, temperatures of respective chips are estimated using the temperature sensors provided for each of the chips, rises in temperatures of the chips are estimated using an output current and mapping, and a temperature of cooling water is estimated for each of the chips by using the temperatures of the chips and the rises in temperatures estimated for the chips. Then, the failure detection device calculates the absolute values of differences in temperatures of the cooling water that have been estimated for the chips, and determines that temperature sensors are normal when all the absolute values are equal to or lower than a predetermined threshold value, and determines that any one of the temperature sensors has failed when any one of the absolute values is higher than the threshold value.